Complete coupling of connector members is important to make certain that the electrical contacts thereof are properly mated for optimum electrical operation, especially in areas where visual indication of fully mated connectors is impossible or difficult to discern.
U.S. Pat. No. 3,901,574 discloses an electrical connector including a plug and receptacle threadably fastened to one another by a flexible plastic coupling ring. A lug on the flexible coupling ring passes over a boss member contained within the matable threaded sections causing the coupling ring to deform so that the lug member seats in position adjacent the boss member emitting an audible sound in so doing. Such an arrangement cannot be used with metal shells housing the plug and receptacle and a metal coupling ring.
U.S. Pat. No. 4,059,324 discloses an electrical connector having a plastic coupling member freely rotatably mounted on one plastic housing member which is matably engagable with another plastic housing member. The coupling member and the other housing member are threadably connected together to connect the matable housing members and the electrical contacts therein. A projection and slot arrangement is located on the coupling member and the other housing member which, when the housing members are mated at the fully-mated condition, visually indicates such condition. This arrangement also cannot be used with metal shells and a metal coupling ring.